Process for the manufacture of sulphuric acid by the contact process



.aan 16, 1925.

O. BEZANSON PROCESS FOR THE MANUFACTURE OF SULPHURIC kAGID .BY THE CONTACT PROCESS Filed Sept. 24. 1923 gnmnto/o 6AM @2W $1, WW* www.

Patented June 16, 1925.

UNITED STATES PATENT OFFICE.

OSBORNE BEZANSON, OF WOBUBN, MASSACHUSETTS, ASSIGNOR T0 MERRIMAC CHEMI- GAL COMPANY', 0F WOBURN, MASSACHUSETTS, A lCORPORATION 0F MASSACHU- SETTS.

PROCESS FOR THE MANUFACTURE OF SUI-PHURIC ACID BY THE .CONTACT PROCESS.

Application led September 24, 1923. Serial No. 664,557,

To all whom t may concern:

Be itvknown'that I, OsBoRNE BnzANsoN, a citizen of the United States, residing at W0- burn, in the county of Middlesex and State of Massachusetts, have invented certain new and useful Improvements in Processes for the Manufacture of Su'lphuricv Acid by the Contact Process, o f which the following is a specification.

This invention relates to improvements in the contact processfor the manufacture of sulphuric anhydride and sulphuric acid The usual practice in the manufacture of sulphurio acid by the contact process involves in general, burning a sulphur containing 'material such as pyrite to produce sulphur dioxid, cooling fthe burner gases to a relatively low temperature and purifying them by a plurality of treatments including ordinary filtration and scrubbing, and then reheatingthe gases and passing them to the converter or contact mass. In the process as it is usually practiced the heat of the hot burner gases is lost or wasted and the gas-purifying process gfiltration, scrubbing, etc.) is not only expensive, involving the use of expensive apparatus and material, the employment of considerable labor, and the exwpenditure of ower for handling the gases and the scrub ing liquid, but is also more or less unsatisfactory.A Also in some of the rocesses now 'in extensive commercial use itis customaryto use fuel for reheating the puried gases, thus adding a further expense to the process, and if cooling of the ycon-, verters 1s necessary, as it freuently is, the heat taken therefrom ordinari y is wasted.

It has been proposed to avoid the mentioned purification, and incidentally the extensive cooling and reheating of the gases referred to, by using as the raw material Afor the roduction of the sulphur dioxid Louisiana brimstone and by maintaining the gases throughout the plrocess at a .highftemperature (not below t e temperature required for the producten of sulphuric anhydrid in the converter), see for instance Patent No. 1,384,566 'to Merriam. y It has also been pro,-y osed to conserve the heat of the gases by heat interchange from the gases to be cooled yat onel stage of the process to the gases to be heated at another stage of the process see for instance Patent No. 1,405,669 to Chase and Pierce.

My invention relates to a process of this general type in which in addition to the elimination of extensive purifying procedure yand accurately maintained.

My invention involves broadly the use of ksteam as the cooling medium and more specifically it involves a novel and highly advantageous method of handling the steam, whereby not only is the temperature of the gases in the various stages of the process maintained at .the point most suitable but the excess of heat is .used for the generation of steam which may be withdrawn and used for any desired purpose.

In the preferred embodiment of my invention which will be described in detail hereinafter by way of illustration, steam which preferably is dry is supplied from a boiler to the cooler for the burner gases and to the converter and the resulting superheated vsteam is returned to the boiler where its superheat is used' for the generation of more .cooling steam, the excess of steam so produced being withdrawn from the system for 'use as desired, for instance, for the genera- -tion of power. e

On the drawings,

Fig. 1 is adiagrammatic illustration of the several parts of the apparatus on which the movement of the ases is indicated by suitable legends; an n i Fig. 2 illustrates one form of apparatus suitable for carr ing out the process.

Referring to ig. 1, l represents the sulphur burner; 2 a combustion chamber for the gases leaving the burner 1 in which the oxidation of any volatilized elemental sulphurtakes place.; 3 a by-pass for the burner gases from the combustion chamber 2 around vthe cooler 4 to the filter 5; 6 a converter,'and 11y a steam generator provided with a water supply, a steam discharge, andp-arallel connections 7 and 8 `for the delivery of cooling steam to the cooler 4 and the converter 6 and parallel connections 9 and 10 for the delivery of the resulting superheated steam back to the fan 12.

The apparatus as it is illustrated in Flg. 2 comprises a sulphur burner 1 which may be of any suitable type, for instance a socalled Glen Falls burner, which discharges into the lower end of the vertical cylindrical combustion chamber 2, the gases leaving the u per end thereof and passing through the y-pass 3 to the filter 5 or through the cooler 4 which may be of any suitable construction, for instance, that :of a tubular boiler. Cooling steam is supplied to the cooler 4 from the boiler 1l through the pipe 7 and the superheated steam produced in the cooler is returned to the boiler through the pipe 9 by the fan 12. The burner gases leaving the cooler 4 pass by way of pipe 13 into the flter-5 and therefrom by way of pipe^14 into the top of the converter 6. The converter may be of any suitable construction but so designed that the contact mass is supported in heat transfer relation to'the steam supplied thereto from the boiler. For instance, the converter may be in the form of a tubular boiler in which the contact mass is held in the tubes and steam is passed through the surrounding jacket. team is supplied to the converter from the boiler through the pipe 8 and returned from the converter to the boiler by the pipe 10 and fan 12. The gases leaving the converter at the bottom pass by way of the pipe 15 to the usual SO3 recovering apparatus (not shown).

An example of the operation of the process is as follows:

Sulphur is burned in the burner 1 and the resulting gases at about 1000 vF. pass to the combustion chamber 2 where the oxidation of any unburned sul hur is completed. The gases leave the com ustion chamber 2 at about 1400 F. and pass to the cooler 4 where they are cooled to about 700 F. by heat interchange with steam supplied from the boiler 11 at yabout 400 F. The cooled burner gases are then passed through the dry filter 5 for the removal of dust and then to the converter 6 which is also supplied with steam from the boiler ll at about 400 F. The gases pass then fromthe converter 6 to the SOs recovering apparatus. The steam after passing through the cooler 4 and the converter 6 in parallel-and which is at a temperature somewhat above 400 F., say

600 F., is delivered by the fan 12 to the boiler 11 where its superheat or a part .of it 1s used for thegeneration of more steam.

This may be done for instance byfusing the superheated steam as the heating'gas in an ordinary tubularboiler oras is illustrated by delivering the superheated steam and a regulated spray of water into a chamber,

whereby the steam is cooled the ected ieaesa water vaporized. The required quantity of the resulting steam is returned to the cooler 4 and the converter 6 for cooling or regulating the temperature thereof as described and the excess of steam produced in the boiler is delivered through the pipe 16 for use as desired.

In connection with the foregoing specific disclosure it is of course understood that. the invention is not limited to the -articular procedure and conditions descri d. For instance, it is conceivable that the vapor of liquids other than water might be used .as the cooling medium but water appears to be the most suitable material'for use on account of its low cost. The steam temperatures referred to, that is, 400 F. for the cooling steam and 600 F. for the superheated steam, may be varied. For instance, the cooling Vsteam may have a lower temperature and the superheated steam a higher temperature.

course may vary with the ltype of apparatus used, etc. It maybe that under some circumstances the steam will serve as a heating The temperatures ofthe steam of l medium for the converter rather than as a cooling medium or it may serve to cool one zone and heat another zone. rllhe essential feature in this connection is that the temperature of the converter is regulated and maintained at the preferred point by means of steam. The gas temperatures mentioned also are merely illustrative and may vary considerably, depending upon the concentration of the burner gases, construction of fiues, nature oractivity and arrangement of contact mass, etc., as will be apparent to one skilled in the art. The principal feature to be observed in the control of the process is that the burner gases are cooled down only to a temperature at which they may be advantageously delivered to the converter without however vpermittin the temperature to go to the point at w ich the combination of water in the air enterin the s stem with the burner gases will com ine wlth SO3 to form sulphuric acid mists. By oper atin in this manner the fication of the gases, including filtration and scrubbing to remove sulphuric acid mists-and fogs, drying and remoistening, andcooling and reheating are avoided and the econom of the process and apparatus is correspon ingly increased.

It is noted that the process and apparatus employed in accordance with my invention are both very simple and inexpensive as compared with the process and apparatus in current use heretofore referredrto. Itcom'- bines the features of maintainin the temperature of the gasesand the 4incident elim- 'ination of expensive purifying apparatus and procedure with easy and accurate temperature regulation andheat economy. l.

expensive puriy A ,feature of the inventionis the very low resistance of the entire to the passage of ases with the consequent advanta s, no-

tab y low consumptionof power or the mechanical operation of the process.

'The' automatic regulation of the various operations of the process such as the supply said source ofv supply.

of sulphur and air to the burner, the supply of cooling steam to the cooler and converter,

to relatively hotter sulphurous gases and returning the resulting superheated steam to 2. "In processes for the manufacture of l sulphuric acid by the contact process involvthe passage of hot gases through a pluin f raIity of instrumentalitles in succession, the y step which consists in passing a plurallty of arallel streams lof r atively cooler steam rom a single source of supply into heat transfer relation to the gases in a plurality of said instrumentalities.

3. In processes for the manufacture of sulphuric acid by the contact process involving the passage of hot sulphur dioxid lcontaining gases successively through a cooler vand a converter, the step which consists in passing steam from a source of supply into eat transfer relation -to the gases 1n the cooler and in the converter and returning -the same to the vsource of supply and employing the superheat thereof for the generation of steam.

4. In the process of making sulphuric acid by the contact process by passin hot burner gases containing sulphur ioxid through a cooler and a converter in succession, the steps which consist in generating steam at a temperature of about 400 F., passing the steam in heat transfer relation to the gases passing through the cooler and the converter, contacting the resulting steam with Water in quantity sufficient to reduce the temperature thereof to about 400 F. and to convert said water into steam at said temperature, passing a part of the resulting steam through the cooler and the converter in afsucceeding cycle. of the operation, and

withdrawing the remainder of said resulting steam from the process.

5. In the process forA the manufacture of sulphuric acid in which hot burner gases are passed through a cooler and then without further substantial temperature change into a converter, the steps comprising circulating parallel streams of steam from a steanr generator into heat transfer relation to the gas in the cooler and converter and backto the steam generator.

6. Apparatus for the manufacture of sulphuric acid comprising in combination with a source of hot burner gases containing sul- .phur dioxid, a cooler and a. converter, a

'zov

steam generator, and means for delivering separate streams of steam from said generator through said cooler and` said converter Vandback to said generator.

In testimony whereof,

I aix my ture.

- OSBOBNE BEzaNsoN. 

